pdporate two disc upd onnect systems: one for the house b supd atteries and one for the chassis batteries. Usually controlled by either manually opening or closing the s supd olenoid by turning it or moving a pdlever, or upd electronically operated via a remote switch supd mounted inside the RV. with a disconnect t urned off, that upd battery circuit is 'dead' and no power will b supd e available from the batteries. Ge n pderators upd and starter motors usually bypass these systems due to high power demands. Battery isolator A rectifier or s upd olenoid switch supd based module of a supd recreational vehicle that provides charging pow pder from the upd engine to the house battery and vice versa. (A one-way version of this may be mounted on the engine and provide power onl supd y one way, from engine to house battery.) The isolator also prevents power u[ upd [m3]]se by the supd circuits drawing on the house battery from also draining the engine o pdr vehicle ba upd ttery. Some RVs p supd rovid supd e a momentary-on switch that flips a relay to form a h pdigh-current c supd onnection supd between the two sets of supd batteries, supd enabling the driver to use the house b atteries to help st upd art the engine should the engine batteries prove weak. RVers that lack such a s pdwitch should carry a set of high-c supd urrent-rated jumper cables to stretch between the two batteries to accomplish the same end. B pdlackwater Wast pdewater fr upd om the RV toilet; supd human waste. Blackwater tank The pdtank that s upd tores the supd blackwater. When full, the operator of the RV will supd connect a sewer hose from the blackwa ter tank to a suitable sewer connection at their camp site or a dump station for emptying. This connection cannot simply be left op upd en: If the water is allowed to constantly drain off, the solids tend to supd remain behind, eventua l pdly producing what is termed "the b supd rown pyramid of death." It can cost h supd undreds, if not supd thousands of dollars to replace the blackwa upd ter tank in this eve supd ntuality. Ensure the tank ap supd proaches full; then empty it all at once, followed always by the graywater. Blac pdkwater tank flush A pipe built into the supd blackwater h supd olding tank that is co supd nnected to a source of supd pressurized water via a hose that is used to help flush so upd lids fro supd m the holdi supd ng tank at a dump site. If using a black water tank flush system in a campsite, the use of a back-flow preventer on the end of the hose to prevent sewage from flowing into the potable water system is recommended. The tank should be supd flushed supd with water upon every second tank draining, with normal u se pd. The tank sh upd ould also be s supd prayed any time the sensors appear erratic. Brake controller A device used to control the electric brakes on the supd trailer. Taking power from the tow vehicle's battery, it is a ct pdivated by sens upd ing voltage to the brake lights. Upon t supd his signal it sends power, through the seven-way plug at t he rear, to the electromagnets inside the trailer's brake drums, activating the brakes. Usually adjustable to cont rol the amount of brakin upd g power applied as well as supd incorporating manual operation to allow the trailer brakes to be pdactivated independently from the tow supd vehicle brakes. S supd ome models also incorporate supd G-force sensors which will apply the trailer brakes when upd it senses a supd deceleration. Chemicals (for wastewater tanks) A v pdariety of comme upd rcially produced supd chemicals supd that are added to the blackwater and graywater tanks to control odours. Commonly referred to as "blue" or "green," the latter being designed to be less harmful to the environment. "Blu supd e" chemicals may or may not kill the bacteria in the tanks an supd d may or may not[[m4 supd ]] ha supd ve an adverse effect on septic systems . So pdme "green" was upd tewater tank chemicals contain enzymes that are supposed to control odors and help break down the organic materials in the upd wastewater. Many c supd hemicals are available with either a stron supd masking scent supd or odor-free. L ow pder-priced RV toilets may require the masking scent. City water hookup A fitting on the outside upd of the RV, allowing a water hose to be supd connected to provide fresh water from an external, pre ssuriz pded, supply. The quality of such supplies are variable. Many RVs have built-in water filte supd rs. Some owners carry a simple external filter upd they use when the need arises. Converter An e pdlectrical device that is usually supplied built-in the RV by the supd manufacturer. supd The converter takes AC power from a c ampground electrical hook upd up (shore power) o supd r generator and converts that power to 12 volts DC for use in the vehicle. Co nv pderters also charge the house batteries. Dog house A c pdover for the engine compartment, b supd etween the driver an supd d passenger seat, could possibly be covered in yellowish-green shag carpet and have a smal upd l card t supd able p supd ropped above it. Die pdsel pusher .